1. Field of the Invention
The present invention relates to a scheme for transferring data that require the copyright protection, through radio.
2. Description of the Related Art
In recent years, the digital network technology has been developing rapidly. There is no limit to the advance of the network technology such as portable telephone and Internet, and its applications are not limited to just the speech communications and becoming more diverse. The typical examples of such diverse applications include the music distribution on the Internet and the music distribution through a radio data network (i-mode, etc.) using portable telephones.
On the other hand, a new field called digital home electronics is also attracting much attention. This is a new home electronics technology utilizing the digital technology, and in particular, fields such as digital broadcasting and “digital AV home electronics” that utilizes the digital AV technology such as MD, DVD, etc. are expected to have considerable growth potential.
A field of “network home electronics” can be regarded as an amalgamation of these fields. In this field, the digital AV data (MPEG2 video, etc.) can be exchanged through networks such as IEEE 1394, and there is potential for newly creating many applications.
Under such circumstances, the problem of the copyright protection requires much consideration. The digital data have an advantageous feature in that they can be easily processed or stored without any degradation, but this feature in turn implies that they can be easily copied. Consequently, the digital data (such as those of movies or music, for example) that are intended to be purchased in exchange to some payment can be easily copied and acquired or transferred illegally.
For this reason, it is important to construct a mechanism for preventing the illegal act with respect to the copyright protected digital data.
A representative example of such a mechanism is DTCP (Digital Transmission Contents Protection) of the IEEE 1394. This mechanism prevents the eavesdropping by the third party by carrying out the authentication and key exchange procedure between a transmitting device and a receiving device of the AV data on the IEEE 1394 so as to share an encryption key for encrypting or decrypting the AV data, and transferring the AV data on the IEEE 1394 after encrypting the AV data by using this encryption key. This mechanism also incorporates a mechanism for preventing the illegal copy by an illegal receiving device by permitting the above described authentication and the key exchange (more specifically, the exchange of Certificate) only between those devices for which the safety is guaranteed in advance.
However, this mechanism presupposes the wired network such as IEEE 1394 or USB. In the case of the AV data transfer using the radio network, the AV data can be transferred between any devices (there is no need to connect devices through a cable so that it is possible to receive the AV data by simply commanding transmission via the radio), so that the third party can eavesdrop the AV data and the illegal act cannot be prevented.